The present invention relates to a liquid crystal display, and more particularly, to a backlight assembly for a liquid crystal display with a support structure that integrates a lamp holder with a diffuser plate prop, more particularly, to a backlight assembly for a liquid crystal display with a support structure that prevents dark zone ,and more particularly, to prevent generating dark band.
One type of flat panel display is a liquid crystal display(LCD). LCDs are finding increasing use in laptop and desktop computers, as large monitors of 30 inches or greater, and as wall-mount TVs.
Most LCDs require an illumination source, or backlight assembly, for backlighting the LCD panel so that an imaged displayed on the LCD panel can be observed by a viewer. Backlight assemblies may be classified into two types : edge type and direct type. Direct type backlight assemblies are typically used in large sized LCDs of 30 inches or greater.
The direct type backlight assembly typically includes a plurality of cylindrical-shape lamps, a reflector sheet and a diffuser plate. The reflector sheet reflects light irradiated from the lamps in the display area so as to avoid loss of light. The diffuser plate diffuses light in an upper portion of the lamps to emit uniform light.
One problem associated with conventional backlight assemblies, especially those sized for use in large sized LCDs, is that the diffuser plate and the lamps tend to sag and/or deform due to their large size. Specifically, the large diffuser plate tends to sag because it is relatively heavy compared to its thickness, which is typically only about 2 to 3 mm. In addition, the heat of the lamps and moisture from the environment tend to cause the diffuser plate to deform. The lamps tend to sag and/or deform because they usually have a length of 30 inches or longer and a diameter of only about 3 to 4 mm. The sagging and/or deformed diffuser plate and/or lamps produce a non-uniform light, which undesirably causes dark and bright spots in the image displayed on the LCD panel.
To prevent the diffuser plate from sagging, various types of structures have been developed in the prior art. For example, spacer pin structures have been developed, which extend between the diffuser plate and the reflection sheet to prevent the diffuser plate from sagging and deforming. However, these spacer pin structure do not address the sagging and deforming lamp problem.
Other structures have been developed in the prior art, which attempt to address both the sagging diffuser plate and the sagging lamp problem. These supporting structures combine a lamp holder with a spacer pin structure. One difficulty with these structures is that lamp breakage can occur because the lamps are seated directly on rigid lamp holder portions. Moreover, external impacts or oscillations experience by the LCD display can cause the lamps to escape from the holders.
Referring FIGS. 1A and 1B, an O-ring 15 encircles a section of the lamp 10 supported by the supporting structure for cushioning.
There is, however a cushioning problem between the lamp and the supporting member. To increase a cushioning member, an O-ring 15, disposed about the supporting structure to cover a section of the lamp 10, helps to cushion the lamp and the supporting structure. In the FIGS. 1A and 1B, the supporting member is omitted, revealing the O-ring 15 and the lamp 10. When the lamp 10 encounters force, the O-ring 15 provides cushioning between the lamp 10 and the supporting member and prevents breakage of the lamp 10. A conventional O-ring is made of resilient, transparent material, i.e. a transparent silica gel to prevent generating dark points on an LCD. When the backlight module lightens, heat is transmitted from the lamp to the supporting member via the O-ring being installed completely therebetween. Because the contact area between the O-ring, the lamp and the supporting member is more extensive, the heat conduction velocity is faster, thus, the temperature around the section of the lamp contacting the O-ring is decreased. The lamp, CCFL, generates varied brightness with varied temperature. The temperature in CCFL is too low, thus, the mercury therein can not be evaporated to make brightness of the supporting member dark, causing brightness of the LCD non-uniform.
Accordingly, a lamp holder and diffuser plate support structure for LCD backlight assemblies is needed that overcomes the deficiencies of the prior art.